The surveillance of persons in airports and, more generally, in public places, has become a public safety need. Devices are already in use for the detection of dangerous objects in the airports, and more particularly for prohibited objects hidden by passengers before embarkation. It is known practice to use metal detectors. However, there are non-metallic dangerous objects, in particular explosive products which are undetectable with such devices.
It is also known practice to use X-ray images to detect the presence of suspicious objects carried by passengers. To this end, the entire length of the body of the passengers has to be scanned by X-ray. This solution poses public health problems through exposure to the X-rays and above all it does not make it possible to handle significant flows of passengers because the processing time cannot be compressed. There are radar imaging solutions which could partly overcome these problems but they are costly and complex to implement.
A French patent application FR 03 06429 describes a device making it possible to partly address these problems. The device comprises an antenna of cylindrical type which presents certain drawbacks, particularly with regard to the microwave leaks.